-- Set your users current location in LAT/LONG here
set @lat=51.891648;
set @lng=0.244799;

-- The main SQL query that returns the closest 5 airports.
SELECT id, icao, lat, lng, 111.045 * DEGREES(ACOS(COS(RADIANS(@lat))
 * COS(RADIANS(lat))
 * COS(RADIANS(lng) - RADIANS(@lng))
 + SIN(RADIANS(@lat))
 * SIN(RADIANS(lat))))
 AS distance_in_km
FROM airports
ORDER BY distance_in_km ASC
LIMIT 0,5;